Breeding system and bird pollination of Camellia pubipetala, a narrowly endemic plant from karst regions of south China

Abstract

Camellia pubipetala is an endemic and endangered species with small and isolated populations occurring only in karst regions in Guangxi of south China. To understand the reproductive biology of C. pubipetala and its possible influences upon its endangered status, its breeding system and pollination ecology were studied in the Longhushan (LHS) and Longzhao (LZ) populations of this species. The flowering duration of the C. pubipetala populations spanned from late January to early April and anthesis of a single flower usually lasted 5-7 days. This species is homogamous, and the pollen and stigma are viable throughout anthesis. Each bagged flower could secrete 141.5 μL of nectar at a sugar concentration of 25.0% during anthesis. The observed high pollen/ovule ratio, and the results of hand-pollination experiments indicated that this species obligately outcrosses. Open pollination resulted in a significantly decreased fruit set (6.7%) and seed set (38.9%) compared to supplementary pollination treatment (23.3% and 64.7%, respectively), which is indicative of a pollen limitation in the process of pollination. The primary pollinator of C. pubipetala is the sunbird Aethopyga christinae and its visiting frequency is quite low, whereas the honeybee Apis cerana is only an occasional pollinator in wild populations. Low reproductive rates in C. pubipetala were found to be a consequence of few species of pollinators and their low visiting frequency. Pollen limitation may be a crucial factor that contributes to the endangered nature of this species. Artificial pollination and the release of pollinators are effective ways to increase the fruit and seed yield of this species. K E Y W O R D SCamellia, nectar properties, pollen limitation, pollen viability, sunbird

Flower biology of the cactus Coryphantha elephantidens in the tropical dry forest of Central Mexico

“…For instance, differential visitation by small and large bees, flies and butterflies, influences corolla length and opening in the Liliaceae Hosta longipes (Yamada & Maki, 2014). In the rare Camellia pubipetala , the low frequency of pollinators is the main cause of low fruit set (Chai et al, 2019). Thus, the maintenance of diverse native vegetation is central to preserving pollinator diversity, which in turn leads to a positive feedback loop in the health of native plant populations.…”

Long‐term progression of inbreeding depression in a Mediterranean ornithophilous shrub

“…As in A. thraskii , the high number of flowers in anthesis at any given time per individual, as well as the behavior of pollinators, facilitates geitonogamy in A. foetida ; because individuals are so close to each other, with intermixed canopies, inbreeding is increased. In addition, we note that a small population size is usually correlated with high values of ID (Nebot et al, 2020; but see Chai et al, 2019).…”

Flowering nectar secretion and pollinators activity of Camellia perpetua in different seasons, a perpetual flowering plant in south China

“…In contrast, much more nectar (summer: 36.12 ± 0.72 μL; winter: 110.8 L±6.02 μL) was secreted during the evening and night (16:00˜8:00 the next day). The production of nectar from a single C. perpetua flower in the summer was comparable to that of C. pubipetala (141.5 ± 11.6 μL) (Chai et al, 2019) andC. nitidissima (157.19 ± 6.34 μL) (Sun et al, 2017) in the same group of Sect.…”